Although VDU users represent the largest group of workers requesting regular
vision screening, many other occupations rely on good eyesight. Vision
screening is, therefore, an important part of any occupational health assessment,
by Karen Sambrook
Over the past decade, the number of employers providing vision screening for
their staff has risen dramatically.
This is largely as a result of the increasing use of computers among office
workers, together with the Health and Safety Executive’s Display Screen
Equipment Regulations (1992), which require employers to provide an eye
examination and vision screening for VDU operators, if it is requested.
"By far the largest number of screenings we do is among this
group," says Nigel Best, an optometrist working for Specsavers opticians
"On average we screen between 20 and 30 VDU operators a week, but in
some of Specsavers’ larger branches this number can be doubled," he adds.
Other major clients, according to Best, include the police (averaging around
10 screenings a week), the armed forces and local industries – particularly
those that require safety spectacles.
Specific visual tests
In addition to the routine eye examination, explains Best, many professions require
specific visual tests, so all Specsavers branches are issued with the
Association of Optometrists handbook, which outlines the visual tests required
by the different professions. For example, the police and most of the armed
forces require members to undergo visual field testing and testing for colour
vision defects. They also demand a higher level of visual acuity.
"Many industries also request colour vision screening," says Best.
"Deficiencies in this area cover a very broad spectrum – from severe
colour defects, where the sufferer is unable to identify primary colours, to a
mild, almost imperceptible, problem. For most jobs a mild colour vision defect
would go unnoticed, but for train operators, who need to identify coloured
signals, or electronic engineers, who need to recognise colour-coded wiring, it
could create a potential hazard."
Professional drivers are another group that is subject to rigorous vision
screening. "Most people who drive for a living – whether fork-lift truck
operators or Formula One racing drivers – require a higher level of corrected
and uncorrected vision than the average road user," points out Karen
Sparrow, senior optometrist at Vision Express.
"They also need to demonstrate enhanced visual skills in other areas,
such as colour and 3D vision," she adds.
Many employers carry out their own vision screening using their own
automated equipment and refer only those individuals with demonstrable problems
to high street opticians. Best describes these devices as "very rudimentary"
and warns that some VDU users with problems may "slip through" such
basic screening programmes.
Automated screening systems may be adequate to assess the vision of staff
who experience no apparent problems in using VDUs, but any staff reporting
visual problems as a result of screen work should undergo a full eye
examination, and this, stresses Best, can only be provided in a high street
practice or a hospital eye department.
"At Specsavers, we routinely screen for glaucoma, diabetes and
cataracts as part of the optometrist’s duty of care and all these procedures
would be less accurate outside the practice," he says.
Visual field screening – one of most requested tests – would prove difficult
elsewhere, he points out, as it requires heavy, bulky equipment that is
difficult to transport.
Sparrow agrees that a full eye examination carried out at the opticians is
the best option for occupational vision screening: "Eye examinations need
to be conducted in an appropriate environment (with controlled lighting, etc),
and although some big manufacturing companies have a dedicated area for vision
screening, this is costly and most prefer to issue a voucher that can be used
at a local optical practice."
Sparrow admits that in some cases it may help the optometrist to see the
ergonomic environment in which employees are operating, particularly for those
requiring safety spectacles. She argues that usually this can be determined by
a risk assessment carried out by a health and safety officer or by staff
completing a simple questionnaire.
"The screening of VDU users, for example, includes a detailed
questionnaire covering the position of the screen, reflection and
illumination," she says, adding that problems can often be resolved by
small changes to the workstation or to working practices.
"An important part of our role in screening VDU users is to give advice
on issues such as screen breaks and how best to position the screen
monitor," continues Sparrow.
"At Vision Express we recommend that users take a five-minute break
every hour, and that they view the computer monitor from a horizontal or
slightly raised position. Looking upwards puts additional strain on the eye
Vision screening is an important part of occupational health assessment, but
its results cannot be considered in isolation, says Sparrow. Other factors
(often ergonomic) have a bearing on the employee’s visual comfort or
performance and it can be just as important to eliminate these as to identify
an underlying problem.
Vision and VDU work
VDU work also has its own visual
requirements and following the HSE’s regulations, the AOP has issued guidelines
on who qualifies as a VDU user and what should be included in the screening
process. There are five basic tests carried out to ascertain whether there are
visual abnormalities present that might impede VDU use. These cover:
– Visual acuity
– Muscle balance between the two eyes (muscle imbalances or
‘phorias’ are a common cause of headaches amongVDU users)
– Central-field defects (blind spots)
– Near point of convergence
– Clarity (ie no scarring of the lensor cornea)